ddl: fix ddl hang over when it meets panic in cancelling path (#23204) (

#23297)

ddl/db_test.go

@@ -4988,3 +4988,54 @@ func (s *testSerialDBSuite) TestColumnTypeChangeIgnoreDisplayLength(c *C) {
  tk.MustExec("alter table t modify column a bigint(1)")
  tk.MustExec("drop table if exists t")
 }
+
+// Close issue #23202
+func (s *testSerialDBSuite) TestDDLExitWhenCancelMeetPanic(c *C) {
+ tk := testkit.NewTestKit(c, s.store)
+ tk.MustExec("use test")
+
+ tk.MustExec("drop table if exists t")
+ tk.MustExec("create table t(a int, b int)")
+ tk.MustExec("insert into t values(1,1),(2,2)")
+ tk.MustExec("alter table t add index(b)")
+ tk.MustExec("set @@global.tidb_ddl_error_count_limit=3")
+
+ failpoint.Enable("github.com/pingcap/tidb/ddl/mockExceedErrorLimit", `return(true)`)
+ defer func() {
+ failpoint.Disable("github.com/pingcap/tidb/ddl/mockExceedErrorLimit")
+ }()
+
+ originalHook := s.dom.DDL().GetHook()
+ defer s.dom.DDL().(ddl.DDLForTest).SetHook(originalHook)
+
+ hook := &ddl.TestDDLCallback{Do: s.dom}
+ var jobID int64
+ hook.OnJobRunBeforeExported = func(job *model.Job) {
+ if jobID != 0 {
+ return
+ }
+ if job.Type == model.ActionDropIndex {
+ jobID = job.ID
+ }
+ }
+ s.dom.DDL().(ddl.DDLForTest).SetHook(hook)
+
+ // when it panics in write-reorg state, the job will be pulled up as a cancelling job. Since drop-index with
+ // write-reorg can't be cancelled, so it will be converted to running state and try again (dead loop).
+ _, err := tk.Exec("alter table t drop index b")
+ c.Assert(err, NotNil)
+ c.Assert(err.Error(), Equals, "[ddl:-1]panic in handling DDL logic and error count beyond the limitation 3, cancelled")
+ c.Assert(jobID > 0, Equals, true)
+
+ // Verification of the history job state.
+ var job *model.Job
+ err = kv.RunInNewTxn(s.store, false, func(txn kv.Transaction) error {
+ t := meta.NewMeta(txn)
+ var err1 error
+ job, err1 = t.GetHistoryDDLJob(jobID)
+ return errors.Trace(err1)
+ })
+ c.Assert(err, IsNil)
+ c.Assert(job.ErrorCount, Equals, int64(4))
+ c.Assert(job.Error.Error(), Equals, "[ddl:-1]panic in handling DDL logic and error count beyond the limitation 3, cancelled")
+}

ddl/ddl_worker.go

@@ -582,12 +582,55 @@ func chooseLeaseTime(t, max time.Duration) time.Duration {
  return t
 }
 
+// countForPanic records the error count for DDL job.
+func (w *worker) countForPanic(job *model.Job) {
+ // If run DDL job panic, just cancel the DDL jobs.
+ job.State = model.JobStateCancelling
+ job.ErrorCount++
+
+ // Load global DDL variables.
+ if err1 := loadDDLVars(w); err1 != nil {
+ logutil.Logger(w.logCtx).Error("[ddl] load DDL global variable failed", zap.Error(err1))
+ }
+ errorCount := variable.GetDDLErrorCountLimit()
+
+ if job.ErrorCount > errorCount {
+ msg := fmt.Sprintf("panic in handling DDL logic and error count beyond the limitation %d, cancelled", errorCount)
+ logutil.Logger(w.logCtx).Warn(msg)
+ job.Error = toTError(errors.New(msg))
+ job.State = model.JobStateCancelled
+ }
+}
+
+// countForError records the error count for DDL job.
+func (w *worker) countForError(err error, job *model.Job) error {
+ job.Error = toTError(err)
+ job.ErrorCount++
+
+ // If job is cancelled, we shouldn't return an error and shouldn't load DDL variables.
+ if job.State == model.JobStateCancelled {
+ logutil.Logger(w.logCtx).Info("[ddl] DDL job is cancelled normally", zap.Error(err))
+ return nil
+ }
+ logutil.Logger(w.logCtx).Error("[ddl] run DDL job error", zap.Error(err))
+
+ // Load global DDL variables.
+ if err1 := loadDDLVars(w); err1 != nil {
+ logutil.Logger(w.logCtx).Error("[ddl] load DDL global variable failed", zap.Error(err1))
+ }
+ // Check error limit to avoid falling into an infinite loop.
+ if job.ErrorCount > variable.GetDDLErrorCountLimit() && job.State == model.JobStateRunning && admin.IsJobRollbackable(job) {
+ logutil.Logger(w.logCtx).Warn("[ddl] DDL job error count exceed the limit, cancelling it now", zap.Int64("jobID", job.ID), zap.Int64("errorCountLimit", variable.GetDDLErrorCountLimit()))
+ job.State = model.JobStateCancelling
+ }
+ return err
+}
+
 // runDDLJob runs a DDL job. It returns the current schema version in this transaction and the error.
 func (w *worker) runDDLJob(d *ddlCtx, t *meta.Meta, job *model.Job) (ver int64, err error) {
  defer tidbutil.Recover(metrics.LabelDDLWorker, fmt.Sprintf("%s runDDLJob", w),
  func() {
- // If run DDL job panic, just cancel the DDL jobs.
- job.State = model.JobStateCancelling
+ w.countForPanic(job)
  }, false)
 
  // Mock for run ddl job panic.
@@ -690,27 +733,9 @@ func (w *worker) runDDLJob(d *ddlCtx, t *meta.Meta, job *model.Job) (ver int64,
  err = errInvalidDDLJob.GenWithStack("invalid ddl job type: %v", job.Type)
  }
 
- // Save errors in job, so that others can know errors happened.
+ // Save errors in job if any, so that others can know errors happened.
  if err != nil {
- job.Error = toTError(err)
- job.ErrorCount++
-
- // If job is cancelled, we shouldn't return an error and shouldn't load DDL variables.
- if job.State == model.JobStateCancelled {
- logutil.Logger(w.logCtx).Info("[ddl] DDL job is cancelled normally", zap.Error(err))
- return ver, nil
- }
- logutil.Logger(w.logCtx).Error("[ddl] run DDL job error", zap.Error(err))
-
- // Load global ddl variables.
- if err1 := loadDDLVars(w); err1 != nil {
- logutil.Logger(w.logCtx).Error("[ddl] load DDL global variable failed", zap.Error(err1))
- }
- // Check error limit to avoid falling into an infinite loop.
- if job.ErrorCount > variable.GetDDLErrorCountLimit() && job.State == model.JobStateRunning && admin.IsJobRollbackable(job) {
- logutil.Logger(w.logCtx).Warn("[ddl] DDL job error count exceed the limit, cancelling it now", zap.Int64("jobID", job.ID), zap.Int64("errorCountLimit", variable.GetDDLErrorCountLimit()))
- job.State = model.JobStateCancelling
- }
+ err = w.countForError(err, job)
  }
  return
 }

ddl/index.go

@@ -618,6 +618,12 @@ func onDropIndex(t *meta.Meta, job *model.Job) (ver int64, _ error) {
  // Set column index flag.
  dropIndexColumnFlag(tblInfo, indexInfo)
 
+ failpoint.Inject("mockExceedErrorLimit", func(val failpoint.Value) {
+ if val.(bool) {
+ panic("panic test in cancelling add index")
+ }
+ })
+
  tblInfo.Columns = tblInfo.Columns[:len(tblInfo.Columns)-len(dependentHiddenCols)]
 
  ver, err = updateVersionAndTableInfo(t, job, tblInfo, originalState != model.StateNone)